N-alkyl monoesters of terephthalamic acids are useful as intermediates in the preparation of grease-thickening agents. As described in U.S. Pat. No. 2,820,012 and others, the terephthalamate esters are reacted with metal bases to form metal terephthalamate thickening agents. These thickening agents, when prepared within a lubricating oil, thicken the oil to the consistency of grease.
There are several conventional methods for preparing N-alkyl terephthalamate esters. Most of these processes, however, require multi-step operations resulting in high operating costs and long processing times. In fact, some of these multi-step processes have been known to consume as much time as six days in processing time.